This disclosure generally relates to a device and method for controlling build chamber temperature, and more specifically controlling build chamber temperature in a device and system for three-dimensional fabrication.
Additive manufacturing, also called 3D printing, is generally a process in which a three-dimensional (3D) object is built by adding material to form a 3D part rather than subtracting material as in traditional machining. One basic operation of an additive manufacturing system consists of slicing a three-dimensional computer model into thin cross sections, translating the result into two-dimensional position data, and feeding the data to control equipment which manufacture a three-dimensional structure in an additive build style. Additive manufacturing entails many different approaches to the method of fabrication, including fused deposition modeling, ink jetting, selective laser sintering, powder/binder jetting, electron-beam melting, electrophotographic imaging, and stereolithographic processes. Using one or more additive manufacturing techniques, a three-dimensional solid object of virtually any shape can be printed from a digital model of the object by an additive manufacturing system, commonly referred to as 3D printer.
In a fused deposition modeling additive manufacturing system, a printed part may be printed from a digital representation of the printed part in an additive build style by extruding a flowable part material along toolpaths. The part material is extruded through an extrusion tip carried by a print head of the system, and is deposited as a sequence of roads onto a substrate. The extruded part material fuses to previously deposited part material, and solidifies upon a drop in temperature. In a typical system where the material is deposited in planar layers, the position of the print head relative to the substrate is incremented along an axis (perpendicular to the build plane) after each layer is formed, and the process is then repeated to form a printed part resembling the digital representation.
In fabricating printed parts by depositing layers of a part material, supporting layers or structures are typically built underneath overhanging portions or in cavities of printed parts under construction, which are not supported by the part material itself. A support structure may be built utilizing the same deposition techniques by which the part material is deposited. A host computer generates additional geometry acting as a support structure for the overhanging or free-space segments of the printed part being formed. Support material is then deposited from a second nozzle pursuant to the generated geometry during the printing process. The support material adheres to the part material during fabrication, and is removable from the completed printed part when the printing process is complete.
Some 3D manufacturing systems such as a FDM® fused deposition modeling 3D printers manufactured and sold by Stratasys, Inc. of Eden Prairie, Minn. use a heated build chamber in order to mitigate thermal stresses and other difficulties that arise from the thermal expansion and contraction of build materials during fabrication, using methods such as are disclosed in U.S. Pat. No. 5,866,058. Certain of these systems have limited power input to provide heat for extrusion while also providing heat to the build chamber. Such systems are commercially sold to operate at 15 amp and 120 volts which is the typical household electrical standard in the United States. Thus the thermal environment of the heated build chamber needs to be regulated more efficiently to meet such operating power limitations to supply the needed heat at the build plane while also maintaining a thermal profile conducive to the multiple layers of build already produced and cooling in a manner that avoids deformation of the part being built and provides for the desired incremental cooling of the build.